Asterisk flooded with chan_dahdi.c do_monitor: Read failed with -1

I have an ubuntu server with asterisk downloaded via apt and I have just added a wctdm24xxp card with FXO-FXS modules. now I have lots of this message coming up in the logs:

WARNING[4695]: chan_dahdi.c:12320 do_monitor: Read failed with -1: Invalid argument

This is accompanied by very high CPU and ram usage essentially bringing the server to a grinding halt and an error on dmesg:

[ 3561.591539] asterisk[4695]: segfault at b3150fec ip b73a4b8d sp b3150ff0 error 6 in[b7334000+1a8000]

I have no idea how to track this segfault and how to deal with it.